From df0a31b4eefb6caff82705b8515218d17e0369ae Mon Sep 17 00:00:00 2001
From: Thiago Santos <thiagoss@osg.samsung.com>
Date: Mon, 10 Aug 2015 18:14:39 -0300
Subject: [PATCH] qtdemux: handle empty segments in seeking adjust

If seeking targets an empty segment skip it as there is no media
offset to get from it. Instead look for the next one.

This doesn't make seeking in push-mode work if you seek to an
empty segment but at least won't get you to wrong offsets.

https://bugzilla.gnome.org/show_bug.cgi?id=753484
---
 gst/isomp4/qtdemux.c | 73 +++++++++++++++++++++++++++++++++-------------------
 1 file changed, 47 insertions(+), 26 deletions(-)

diff --git a/gst/isomp4/qtdemux.c b/gst/isomp4/qtdemux.c
index bd4987b..811523c 100644
--- a/gst/isomp4/qtdemux.c
+++ b/gst/isomp4/qtdemux.c
@@ -1234,6 +1234,7 @@ gst_qtdemux_adjust_seek (GstQTDemux * qtdemux, gint64 desired_time,
     GstClockTime media_time;
     GstClockTime seg_time;
     QtDemuxSegment *seg;
+    gboolean empty_segment = FALSE;
 
     str = qtdemux->streams[n];
 
@@ -1247,41 +1248,61 @@ gst_qtdemux_adjust_seek (GstQTDemux * qtdemux, gint64 desired_time,
     seg = &str->segments[seg_idx];
     seg_time = desired_time - seg->time;
 
+    while (QTSEGMENT_IS_EMPTY (seg)) {
+      seg_time = 0;
+      empty_segment = TRUE;
+      GST_DEBUG_OBJECT (str->pad, "Segment %d is empty, moving to next one",
+          seg_idx);
+      seg_idx++;
+      if (seg_idx == str->n_segments)
+        break;
+      seg = &str->segments[seg_idx];
+    }
+
+    if (seg_idx == str->n_segments) {
+      /* FIXME track shouldn't have the last segment as empty, but if it
+       * happens we better handle it */
+      continue;
+    }
+
     /* get the media time in the segment */
     media_start = seg->media_start + seg_time;
 
     /* get the index of the sample with media time */
     index = gst_qtdemux_find_index_linear (qtdemux, str, media_start);
     GST_DEBUG_OBJECT (qtdemux, "sample for %" GST_TIME_FORMAT " at %u"
-        " at offset %" G_GUINT64_FORMAT,
-        GST_TIME_ARGS (media_start), index, str->samples[index].offset);
+        " at offset %" G_GUINT64_FORMAT " (empty segment: %d)",
+        GST_TIME_ARGS (media_start), index, str->samples[index].offset,
+        empty_segment);
 
-    /* find previous keyframe */
-    kindex = gst_qtdemux_find_keyframe (qtdemux, str, index);
+    if (!empty_segment) {
+      /* find previous keyframe */
+      kindex = gst_qtdemux_find_keyframe (qtdemux, str, index);
 
-    /* if the keyframe is at a different position, we need to update the
-     * requested seek time */
-    if (index != kindex) {
-      index = kindex;
+      /* if the keyframe is at a different position, we need to update the
+       * requested seek time */
+      if (index != kindex) {
+        index = kindex;
 
-      /* get timestamp of keyframe */
-      media_time = QTSAMPLE_DTS (str, &str->samples[kindex]);
-      GST_DEBUG_OBJECT (qtdemux,
-          "keyframe at %u with time %" GST_TIME_FORMAT " at offset %"
-          G_GUINT64_FORMAT, kindex, GST_TIME_ARGS (media_time),
-          str->samples[kindex].offset);
-
-      /* keyframes in the segment get a chance to change the
-       * desired_offset. keyframes out of the segment are
-       * ignored. */
-      if (media_time >= seg->media_start) {
-        GstClockTime seg_time;
-
-        /* this keyframe is inside the segment, convert back to
-         * segment time */
-        seg_time = (media_time - seg->media_start) + seg->time;
-        if (seg_time < min_offset)
-          min_offset = seg_time;
+        /* get timestamp of keyframe */
+        media_time = QTSAMPLE_DTS (str, &str->samples[kindex]);
+        GST_DEBUG_OBJECT (qtdemux,
+            "keyframe at %u with time %" GST_TIME_FORMAT " at offset %"
+            G_GUINT64_FORMAT, kindex, GST_TIME_ARGS (media_time),
+            str->samples[kindex].offset);
+
+        /* keyframes in the segment get a chance to change the
+         * desired_offset. keyframes out of the segment are
+         * ignored. */
+        if (media_time >= seg->media_start) {
+          GstClockTime seg_time;
+
+          /* this keyframe is inside the segment, convert back to
+           * segment time */
+          seg_time = (media_time - seg->media_start) + seg->time;
+          if (seg_time < min_offset)
+            min_offset = seg_time;
+        }
       }
     }
 
-- 
2.7.4